Trump is also expected to order the escalation of US operations against Daesh in Iraq and Syria.
President Donald Trump signed an order on Friday to begin what he called a "great rebuilding" of the US armed services, promising new aircraft, naval ships and more resources for the military.
"Our military strength will be questioned by no one, but neither will our dedication to peace. We do want peace," Trump said in a ceremony at the Pentagon.
Trump predicted that Congress, which sets the expenditures for the government, will "be very happy to see" the White House's new spending request for the military.
Trump made clear during last year's presidential campaign and in recent weeks that he wants to enlarge the ranks of the military services and expand its fleets of aircraft and ships.
For example, he said he envisioned a naval fleet of 350 vessels, up from the navy's current 274 and more than its 310-vessel target.
He is also expected to order his new defense secretary, James Mattis, to intensify operations against Daesh in Iraq and Syria with more US soldiers and military hardware like artillery and attack helicopters.
Another expected move is to review and to strengthen US ability to defend itself against cyber attacks and to conduct offensive cyber attacks itself.
The order Trump signed on Friday was less specific, calling for a sweeping 30-day readiness review of the US military, with the aim of preparing new budget requests to improve readiness.
But he has also pressured the Pentagon to cut costs on some of its most expensive programmes.
Trump signed the new order at a ceremonial swearing-in of Mattis as defense secretary, lavishing praise on the retired Marine general.
"Secretary Mattis has devoted his life to serving his country. He is a man of honour, a man of devotion, and a man of total action. He likes action," Trump said.